1. Field of Invention
This invention relates to a method of controlling the operation of a wireless local area network.
The invention also relates to a wireless local area network including a plurality of wireless local area network stations.
2. Background Information
Various methods are known for sharing network communication channels or links among stations in a local area network. One widely used method is known as CSMA/CD (carrier sense multiple access with collision detection). According to this known method, a station wishing to transmit a message listens until the transmission channel is idle before commencing to transmit an information packet. Furthermore, the station continues to listen to the channel after commencing a transmission, and if a collision is detected, that is, more than one station has commenced to transmit an information packet, any station which detects such collision terminates its message transmission and transmits a jam pattern (or garble) such that all other stations can be informed of the collision, terminate message transmission, and wait a random time before attempting to commence a further message transmission.
The CSMA/CD protocol is the subject of an international (ISO) standard and corresponding IEEE Standard, No. 802.3, and has become a generally used protocol for LANs utilizing wired connections for transmission between the stations. In consequence, CSMA/CD LAN controller chips have become widely commercially available. Several manufacturers produce such chips, complying with the IEEE 802.3 standard. An example is the Intel 82586 LAN coprocessor chip, available from Intel Corporation of Santa Clara, Calif., U.S.A. Such chips provide various facilities useful in LANs such as data rate range and a backoff algorithm and configurable parameters such as slot time duration, retry counter offset and limit, and interframe spacing time.
LANs using wired interconnections have the disadvantage that extensive cabling is required to interconnect the stations. The provision of such cabling is generally inconvenient and gives rise to inflexibility if it is desired to alter the physical locations of the stations. It has been proposed to utilize a wireless transmission link to replace the cabling interconnections of a LAN. However, if only a single wireless channel is to be utilized for such a LAN, the normal CSMA/CD protocol cannot generally be applied as in a cable-connected LAN since the transmission and the reception of signals take place on the same channel and a station cannot generally receive (or listen) while it is transmitting because the dynamic range is too large.